The instant invention relates a switch mechanism that has an improved method of operation for use in flashlights. More specifically, this invention relates to an internal, inline switch mechanism for a flashlight that operates in a reverse direction to increase the reliability of the switch and provide an extended switch contact duration.
Flashlights of varying sizes and shapes are well known in the art. A number of such designs are known that utilize two or more batteries as their source of electrical energy, carried in series in a tubular body, where the tubular body also serves as a handle for the flashlight. Typically, an electrical circuit is established from one terminal of the battery, through a conductor to an external switch and then through another conductor to one contact of a bulb. After passing through the filament of the bulb, the electrical circuit emerges through a second contact of the bulb in electrical contact with a conductor, which in turn is in electrical contact with the flashlight housing. The flashlight housing provides an electrically conductive path to the other terminal at the rear of the battery. Actuation of the external switch completes the electrical circuit enabling electrical current to pass through the filament of the bulb, thereby generating light that is then typically focused by a reflector to form a beam of light.
In general, these flashlight switch mechanisms operate in two basic manners. The first mechanism is a pushbutton type switch on the side or bottom of the light. The user depresses the switch, which locks into the engaged position, turning the flashlight on. To turn the light off, the user again depresses the switch, unlocking it and turning the light off. Often, if a watertight seal is desired, a rubberized material is installed into the body of the flashlight as a covering over the switch mechanism. This design has several drawbacks. One drawback is that the increased number of parts creates additional assembly steps and increases the difficulty of assembly process. Another drawback is the possibility of leaks developing as the rubber membrane wears out from the stretching action resulting from continuous use.
In an attempt to resolve the drawbacks noted above with respect to the push-button type switches, a second type of rotatable switch was developed for in-line use in flashlights. In one design, an end cap is rotatably secured to the flashlight body. To establish the required electrical contact, the end cap is rotated making contact to illuminate the lamp bulb. A number of such prior art designs feature rotatable end caps which are rotated to move the batteries longitudinally within the flashlight body towards the lamp bulb, thereby causing contact between the battery contact and the base contact of the lamp bulb. In the open position, the battery is typically spring biased away from the base contact of the bulb.
In other designs, miniature flashlights have been designed where the rotatable switch is located in the reflector end of the flashlight body. The lamp bulb is located within an insulated receptacle at the reflector end of the flashlight with one or more conductive pins being rotatably aligned by movement of the switch portion of the device to establish electrical contact. While these switch mechanisms are internal to the device and thus less subject to damage, they are overly complicated in design and more costly to manufacture and require higher assembly tolerances.
In addition, the types of switches described above all generally operate in a forward direction, meaning that as the user turns the head or tail of the flashlight, tightening it onto the body of the flashlight, switch contact is eventually made thereby turning the flashlight on. Electrical contact, in this type of switch, is achieved by bringing a spring contact on the inside of the flashlight into contact with one pole of the battery contained within the body. These types of switches are problematic because the components of the flashlight are not always firmly holding the batteries in place. For example, when the flashlight is in the off position, the head is generally partially unscrewed from the body of the flashlight, preventing the spring on the back of the head from contacting the battery. This arrangement, however, also prevents the battery from being restrained, allowing the battery to freely float within the flashlight body. In addition, the range of switch contact is very limited, thus providing a very low tolerance switch mechanism that does not operate smoothly.
It is therefore and object of the present invention to provide an improved flashlight switching mechanism that is entirely self contained and completely waterproof. It is a further object of the present invention to provide a switching mechanism for a flashlight that has improved operating characteristics, such as increased contact duration and smoother operation. It is yet another object of the present invention to provide an in-line flashlight switching mechanism that is completely enclosed within the body of a flashlight thereby eliminating the possibility of contamination and damage from external forces.
In this regard, and in furtherance of the above stated objectives, the present invention provides a unique inline switch mechanism that is fully integrated into a flashlight head to provide a completely self contained and waterproof switching mechanism. The present invention further provides an inline flashlight switch mechanism that operates in a reverse direction whereby the switch makes electrical contact as the flashlight head is unscrewed. This is in contrast to the above-described switches that generally operate in a forward direction. This manner of operation allows the present invention to provide an extended operational range of positive electrical contact duration, while also producing a smoothly operating switch having broad operational tolerance.
The basic structure of the switch contains several operational components including a switch housing, a contact tube, a plunger, a contact spring, an insulator disk and a secondary spring. All of the components are electrically conductive with the exception of the insulator disk and the switch housing. The switch housing contains all of the other operational components of the switch and serves to selectively isolate them electrically from the body of the flashlight. In the off position, the plunger floats, centered in the contact tube, with the contact end in electrical communication with the battery. The contact spring is disposed around and is frictionally retained at the end of the plunger opposite the contact end. Both the plunger and the contact spring are in electrical communication thereby making the contact spring and plunger electrically hot. The insulator disk is installed onto the back of the plunger, supporting in the center of the contact tube and electrically isolating it from the walls of the contact tube. The insulator disk is also disposed between the plunger and the secondary spring electrically isolating these two components from one another as well. The secondary spring at one end exerts pressure on the insulating disk and thereby on the plunger maintaining the plunger in contact with the battery at all times during the operational range of the switch. At the other end, the secondary spring is in electrical communication with one contact of the LED bulbs and is also in electrical communication with the walls of the contact tube.
In a normally open position, the contact spring is displaced from the bottom wall of the contact tube. As the flashlight head is unscrewed the switch mechanism, retained within the head of the flashlight, moves away from the batteries while the plunger remains in place in contact with the battery due to the force of the secondary spring. Once the head is displaced far enough, the bottom wall of the contact tube comes into electrical communication with the contact spring allowing electricity to flow to the LED""s. Since the spring force of the contact spring is less than that of the secondary spring, the contact tube continues to move, further compressing the contact spring while maintaining contact with the contact spring and keeping the contact end of the plunger in electrical communication with the battery as the flashlight head is turned through several rotations.
Other objects, features, operational details and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.